Quick connect vacuum system



AOei. 6, 1964 H. s. PHILBRICK, JR

QUICK CONNECT VACUUM SYSTEM 4 Sheets-Sheet 1 Filed April s, 1961 w, gw COct. 6, 1964 H. s. PHILBRICK, JR 3,152,206

QUICK CONNECT VACUUM SYSTEM Filed April 3, 1961 4 Sheets-Sheet 2 Weke# xOct. 6, 1964 H. s. PHILBRICK, JR 3,152,206

QUICK CONNECT VACUUM SYSTEM Filed April 5, 1961 4 Sheets-Sheet 3 INV ENTOR.

Oct. 6, 1964 H. s. PHILBRIQIQJR QUICK CONNECT VACUUM SYSTEM 4Sheets-Sheet 4 Filed April 3, 1961 United States Patent O psi rfhisinvention relates to vacuum tank systems, and particularly to a multipletank system for continuously degassing ladles of molten metal.

In recent years more and more steel is being degassed in order to removeincluded deleterious gases such as oxygen, nitrogen and hydrogen. Theusual mode of degassing molten metal is to subject a ladle of it to avacuurn, either alone or in combination with other processes.

Although the quality of steel is considerably increased the process doescreate some problems. The length of time the molten metal is in transitbetween the furnace and ingot molds is lengthened. This increased timemay necessitate adding superheat to the molten metal, and superheatingtends to wear out furnace linings at a faster than normal rate.

A substantial portion of the increased time is consumed in connectingthe vacuum tank to the vacuum system after the ladle is placed in thetank, and then pumping down the tank and system to a vacuum sufticientto effectively degas the metal.

It is now customary to install a complete vacuum system for each vacuumtank which is to be used for degassing. lf a plurality of tanks are tobe used for degassing, the cost of installing degassing systems ismultiplied by the number of units required. Likewise, the iloor spaceneeded to install the systems is increased by the number of units put inoperation.

Accordingly, a primary object of this invention is to provide a vacuumtank system especially adapted for degassing molten metal in which avacuum tank or a vacuum tight molten metal receptacle such as an openhearth bottle car is immediately connected to a vacuum system as soon asthe tank cover or degassing hood is put in piace to thereby reduce theconnecting and pump-down time.

Another object is to provide a very ilexible vacuum tank system in whicha single vacuum tank hood asser bly, a single lift-and-swing device, anda single vacuum system are arranged to service a plurality of vacuumtanks.

Another object is to provide a vacuum tank hood assembly for a vacuumsystem, said hood assembly having a pair of outlets, each outlet beingconnectable alternately to an ejector system, the other outlet beingautomatically blanked od whenever it is not in use.

Y et a further object is to provide a vacuum tank system requiring aminimum initial investment.

Yet another object is to provide a vacuum tank system in whichproduction need not be discontinued due to maintenance or break down ofa vacuum tank.

A further object is to provide a vacuum tank system which can becontinuously operated, one tank in the system being used while a secondtank is being prepared for the next use.

Yet another object is to provide an open hearth degassing plant in whichmolten metal in a vacuum tight bottle car is degassed between thefurnace and ladle filling pit.

A further object is to provide an open hearth bottle latenteel @ein 6, l

car degassing unit in which a bottle car may be quickly connected to avacuum system to thereby minimize ternperature drop between the openhearth furnace and ladle.

Another object is to provide an open hearth bottle car egassing unitwhich can be easily incorporated into an existing open hearth operation.

Other objects and advantages will become apparent from a reading of thefollowing description of the invention.

The invention is illustrated more or less diagrammatically in theaccompanying drawings wherein:

FIGURE l is a top plan View of the system;

FIGURE 2 is a side elevation of a portion of the system takensubstantially along the line 2-2 of FIGURE l with parts broken away forclarity;

FIGURE 3 is a top plan View to a smaller scale than that of FIGURES land 2 illustrating the vacuum tank hood assembly, parts being brokenaway for purposes of clarity;

FIGURE 4 is a side elevation of FIGURE 3 with parts broken away forpurposes of clarity;

FIGURE 5 is a view taken substantially along the line 5-5 or" FIGURE 3;

FIGURE 6 is a top plan view of another embodiment of the invention; and

FlGURE 7 is an elevation taken substantially along the line of FIGURE 6.

Like reference numerals will be used to refer to like parts throughoutthe following description of the drawings.

The general assembly is illustrated best in FIGURES 1 and 2. In FIGURE la pair of vacuum tank units are indicated generally at lll and lll. Eachunit consists of a vacuum tank l2 which consists of a vertical wallportion i3 Welded at its lower end to a base plate M which in turn restson foundation l5. The joint between wall 13 and foundation plate i4 isair-tight as are all other jonits in the system. ri`he tank is largeenough to accommodate a commercial sized container of molten metal, inthis case a ladle le which may contain anywhere from 2 to 100 tons ofmolten metal. Since the construction of the tank itself and the meansfor supporting and centering the ladle are not essential to anunderstanding of the invention, they are not further illustrated ordescribed.

The upper edge of tank wall 13 terminates in a pair of flanges I7 andi3. Upper flange 1S is suitably apertured to receive a seal l.

A cover or hood assembly is indicated generally at 2%. It consists of adome 2l which terminates at its lower edge in a sealing flange 22.Flange 22 is suitably apertured in opposition to the aperture in flangeil@ so that a seal carried by the flanges forms an air-tight sealbetween the meeting surfaces. A header Z4 is secured to the cover 2l bywelding at 25. The header includes a long horizontal run 26, a pair ofelbows 27 and Ztl, and a pair of vertical runs 29, 3%. A pair ofreinforcing braces 3l, 3?; are welded at their outer ends to the elbowsand vertical runs and to their inner ends to the cover. The bracesstabilize the header with respect to the cover. The lower end of each ofruns 2', is welded to a sealing flange 33, 34 respectively. Each flangeis apertured, as at 35, in line with the internal passage of the header.Extension of flanges 34, 33 are welded to Harige 22.

A blank stand is indicated at 37. The stand consists of a pipe welded atits lower end to a plate 38 which rests on the foundation 15. A solidblank ange 39 is head assembly is set in place.

Y melt and the gases withdrawn from the ladle.

welded to the upper end of the pipe, the upper surface of blank ange 39lying in the same plane as the upper surface of flange l. When the hoodassembly is set in place over the vacuum retort, sealing ange 34 willcontact blank ilange 39 at the same instant cover flange 22 contactstank frange i8. Arly suitable sealing means may be utilized to providean air-tight seal between the header 3d and blank ilange 39.

A vacuum system inlet pipe is indicated at l ipe @il has a sealing ange4l Welded to its upper end, the ange being aligned with ange 33 of run3@ when the ln this instance the elevation of the upper surface ofsealing ange el is substantially identical to the elevation of the lowersurface of llange 33. Any suitable sealing means is provided to form anair-tight seal between the flanges.

A short collar d2 connects pipe d to a vacuum valve 43. rl`he vacuumvalve in turn connects the tank unit to a pump-down system indicatedgenerally at 4d in FlG- URE l. Any suitable vacuum system can be usedwith the illustrated tank unit. In this case a steam ejector system isillustrated. lipe 45 represents the first stage of a multiple stagesystem.

The dimensions of the unit, particularly the elevation of the uppersurfaces of each of flanges 39 and 4l, are stabilized by the reinforcingstructure indicated generally at d'7 and 4d. These stabilizingstructures are essentially repeated on tank unit lll, and accordinglyonly tank unit 11 and FIGURES l and 2 will be referred to.

Each of the stabilizing structures consists of a pair of generallyvertically oriented plates d?, t?, arranged to lie along an extension ofthe diameter of each tank. rhe inner end of the shorter of the twoplates 4%, is welded to the outside of tank wall 13. The outer end ofthe plate is Welded to a Vertical iiange 5l. The inner end of each ofplates 59 is welded to a second vertical frange 52. The outer end ofeach of vertical plates 5d is welded to the blank stand 37 and dischargepipe i9 respectively. A rib S3 on outer plate 52 lits into a matinggroove on plate 5l. and prevents the plates from twisting duetordistorting forces set up by heat given otf from the ladle. Apiurality of generally horizontally oriented reinforcing plates 5d, 5S,56, 5'7 provide additional stability. The generally horizont-allyoriented reinforcing plates of tank unit lil corresponding to plates Sand 55 in tank unit ll. will,

' of course, be so located as to avoid interference with one another.

The vacuum hood assembly and means for positioning it are illustrated inmore detail in FGURES 3, 4 and 5. The header 2d is lined with refractoryo@ which protects the metal shell 6l from direct exposure to the heat ofthe Hood 2l is apertured as at 62 and 63 in line with a pair of matingopenings 6d, 65 in the lower portion of header run 2o. Reinforcingplates 62a and 63a are welded to the inside of the dome shell. Gaseswithdrawn from the ladle of molten metal can therefore leave througheither of openings 62 or 63. in the position of the hood assemblyillustrated in FGURES l and 2, the bulk of the gases will be withdrawnthrough opening 62, 64. When the hood assembly is rotated ninety degreesto overlie tank unit l0, the bulk of the gases will be withdrawn throughopening 63, 65 and leave the tank unit through run 29 which will then beconnected to the outlet pipe 4d.

A short pipe on which terminates in a sealing flange 67 opens into thelong run 26 in line with the center line of the tank. lt is large enoughto permit the insertion and removal of a met-al sampling device or toadmit alloyingelements and/or charge materials to the melt. It isindicated more or less diagrammatically, but it will be understood thatin an actual setup it will be suitably the upper end of the pipe.

The rib locks one plate to the other The hood assembly is moved back andforth between the tank units by a lift-and-swing device indicatedgenerally at '763. In this instance, the lift-and-swing device is avertically extendable and reciprocable ram which raises and lowers theentire assembly, and a horizontally positioned cylinder which rotatesthe hood assembly in a horizontal plane.

The hood assembly is connected to the ram by a supporting structureillustrated best in FIGURES l, 3 and 5. The supporting structureconsists essentially of a pair of generally vertically oriented sideplates 7l, 72, shown est in FIGURES 3 and 5, which are welded at theirinner ends to the lift-and-swing device, as at 73, and at their outerends to the outer shell of the hood assembly, as at 74. A pair of topand bottom plates '75, 76 likewise extend between the collar 7th: of thelift-andfswing device and the tank to provide additional rigidity. Theforwardmost end 77 of top plate 75 is curved upwardly and lies flatagainst the upper surface of the outer shell till of the hood. Threevertical reinforcing brackets 7S, 79 and Sil provide additional support.

Any suitable means may be utilized to rotate the hood assembly so as toalign it with either tank unit lil or 1l. In this instance, a hydrauliccylinder indicated diagrammatically at 34 has been shown. The cylinderis pivoted as at 8l to a stationary support 82. The outer end of thepiston rod 3 is pivotally connected to side plate 72. The swingingpiston is indicated only diagrammatically as it will be understood thatany suitable device, such as a mechanical linkage or a worm gear, forexample, could be utilized to swing the hood assembly from one positionto another.

ln FIGURES 6 and 7, an open hearth degassing plant is illustrated. InFlGURE 6, a degassing station is indicated generally at 86. A rst moltenmetal transfer car, in this instance, a conventional bottle car, isindicated generally at 87, and a second bottle car is indicatedgenerally at S8. Car S8 is at a ladle lling station, indicated generallyat S9. The bottle cars move from station to station Y along tracks 90.The bottle cars are shown in this instance as self-propelled, but itwill be understood that within the scope of the invention the rnoltenmetal transfer cars may be either self-propelled or moved from stationto station by other power means. A charging station, which includes anopen hearth furnace and means for tapping molten metal from the furnaceinto the bottle car, would be located just to the left of degassingstationv 8o with reference to FGURE 6. Since the details of the chargingstation are conventional, it is not further illustrated or described,

Referring now to FIGURES 6 and 7, a closed, vacuum tight tank isindicated at 91. The right end of the tank opens into a conduit 92 whichis connected to a vacuum system, not shown. Arrow 93 indicates the fluidow path through tank 9i when the degassing station is in operation.Since the details of the vacuum system are conventional, they are notfurthe-r illustrated or described.

A multi-stage steam ejector system may advantageously be used.

The left end of tank 9i opens into an upstanding conduit 94 whichterminates at its upper end in a sealing ange 95. Flange 95 isconstructed to make sealing engagement with a similar llange 96 carriedat the lower end of a vacuum connection or conduit indicated generallyat 97. Vacuum conduit 97 consists essentially of a short horizontal runof pipe 98, an elbow 99, a short collar 100 which terminates in flange96, and another short collar lill which terminates at its lower end in asealing ange 102.

Vacuum conduit 97 is welded or otherwise suitably secured to arectangular frame which consists essentially of longitudinal channels103, 194 and cross channels E65,

Y 106. The frame, in turn, is connected by four hydraulic rams 167,fillet, 169, lill to a supporting structure indicatedgenerally at lill.Suitablehydraulic lines under control of a single master valve admithydraulic fluid to the cylinders to raise and lower the frame and vacuumconduit through horizontal planes. A series of rollers 112, 113 carriedby the rectangular frame roll along one of the legs of a series of guidemembers 114, 115 to help maintain the frame and vacuum conduithorizontal during raising and lowering movement.

Bottle car S7, which is essentially a vacuum enclosure suitable forcontaining up to around 200 tons of molten metal, consists essentiallyof a tank portion 121? which is bodily rotatable about trunnions 121,122 by large bull gears 123, 124. A short neck 125, which terminates atits upper end in a sealing flange 126, surrounds an opening in the topof the bottle car when it is in its normal position. Flange 126 meetswith flange 1ii2 and the two flanges form a vacuum tight seal when inengagement.

Referring now to FlGURE 6, a second bottle car is shown lling a ladle13@ at the ladle lling pit or station 89. The car has been rotatedapproximately 90 degrees to a position in which molten metal may bedischarged through the opening defined by neck 12S.

The ladle may be of any conventional size and, accordingly, it is notillustrated in detail. A pair of lifting trunnions are indicated at 132,133 and a stopper rod carrying arm is indicated at 134. It will beunderstood that a stopper rod, not shown, seats in a discharge nozzle135 in the bottom of the ladle. The framework of the pit is indicated at135.

It will be understood that the exact construction of the vacuumconnection surrounding the opening of the bottle car can be variedwithin the scope of the invention. In this instance the actual openingis indicated at 137, and the neck 125 is oblong in shape, as can best beseen from the figures.

The use and operation of the invention is as follows.

The hood assembly 2lb is elevated to the position of FIGURE 4 by thelift-and-swing device 7l?. Assume that the assembly is swung to aposition in which it substantially overlies tank unit 1li. A ladle ofmolten metal 16 is then lowered into position within tank As soon as theladle is positioned, the swinging cylinder de is actuated to swing theentire hood assembly into the position of FIGURE l, overlying tank unit11. lt will be understood that any conventional means may be utilized toinsure that the hood is directly aligned with the flange 13 of the lowerportion of the vacuum tank. Vertical runs 29 and 3l? of the header willthen be precisely aligned with stand 37 and pipe di? respectively. Thelift-and-swing device lowers the hood assembly into the position ofFIGURE 2. Since the meeting surfaces of flanges 33 and 41, 34 and 39,and 22 and 1S lie in the same plane, they will all make sealing contactsimultaneously as the hood assembly comes to rest in the position ofFGURE 2. Since flange 39 is solid and a seal is formed at the jointbetween lianges 34 and 3?, the conduit 29 will be blanked off as soon asthe hood settles in place. If flange 18 is carried by the hood assemblyand a sealing surface is formed between flanges 17 and 18, a closedsystem will again be formed as soon as the hood assembly is lowered intoplace because the parts will be so dimensioned that all will meetsimultaneously.

Although flanges 33 and 34 are illustrated as lying in parallel,coincident planes, the invention is not limited to this particularrelationship of the mating surfaces. It may be expedient, depending onoperating conditions or other factors, to arrange thee flanges inparallel, noncoincident planes. Such a setup is illustrated in FIG- URES6 and 7. 1t is even within the scope of the invention to arrange thesurfaces to meet in non-parallel planes. The machining is facilitated bythe parallelism of the planes however. The really important fact,irrespective of the relationship of the orientation of the meetingplanes with one another, is that the flanges engage simultaneously orwith only a very small lag.

As soon as the hood comes to rest on the top of the tank 12, vacuumvalve 43 is opened and the entire tank unit is immediately connected tothe ejector system. Gases are withdrawn from the tank and molten metalthrough openings 62 and 63 in the hood. The bulk of the gases will passout of the tank and molten metal through opening 62 and go directly intothe vacuum system through header 24, elbow 23, run 3l?, collar d2 andvalve 43. Some gases will, of course, pass out through opening 63 intoheader 24.

As soon as the molten metal is treated, hood assembly 2li is raised,swung over tank unit 1t), and ladle 16 removed. The hood assembly isthen swung back over tank unit 11, another laddle placed in tank unitlll, and the hood assembly is then placed on tank unit 1li. Tank unit 11is then allowed to cool down until the third ladle of molten metal isready for treatment. Tank unit 1li will, of course, cool while the thirdladle is being treated in tank unit 11. Ladles of molten metal maythereby be continuously degassed.

When the header assembly is swung to a position in which it overliesvacuum tank unit 10, the mode of operation will be exactly the sameexcept in this case the bulk of the gases will be withdrawn throughopening 63 since that opening will then lie in the shortest path betweenthe vacuum tank and vacuum system inlet pipe 49.

In the operation of the embodiment of FIGURES 6 and 7, molten metal froman open hearth furnace at a charging station is poured into a properlypositioned bottle car by any conventional means. Pihe car is then movedto the degassing station 86. Hydraulic rams 1W, ldd, lll, 11i? are thenactuated to lower framework 163, 1h14, 165, 136 carrying vacuum conduit97 into the solid line position of FIGURE 7. Vacuum conduit flanges 102,9e mate with flanges 126 and 95, respectively. The anges are sodimensioned that contact is made substantially simultaneously betweenthe two sets of flanges so that a vacuum can immediately be commenced tobe drawn through conduit 92. In this instance, the mating surfaces arein parallel, but not coincident, planes.

After degassing is completed, the hydraulic rams are again actuated toelevate the Vacuum connection to the dotted line position of FIGURE 7.The vacuum conduit is maintained in horizontal planes throughout itsupward and downward movement by virtue of the rolling of rigid framework193, 1M, 195, 1516 along the guide members 114, 115.

After the molten metal has been suiiiciently degassed and the vacuumconduit raised to a position in which it clears the bottle car, the caris then moved to the ladle filling station shown at the right in FIGURE6. The bull gears are then actuated and the car rotated degrees aboutits axis to pour into a ladle 139.

Although a preferred embodiment of the invention has been illustratedand described, it will be understood that various other modificationsmay be made within the scope of the invention. Accordingly, it isintended that the descripuon and drawings be considered illustrativeonly and that the scope of the invention be limited only by the scope ofthe following claims.

I claim:

l. A vacuum system for vacunadegassing molten metals, said systemcomprising a pair of vacuum tanks, said tanks being open at their upperends,

a hood assembly, said hood assembly including a hood engageable with theupper open end of each tank and adapted, when in engagement with a tank,to form an air-tight seal therewith,

a header, said header having an inlet opening into the hood and a pairof outlets, each outlet being connectable, in turn and depending uponthe position of the hood assembly, to

a vacuum system inlet,

a lift-and-swing device, said lift-and-swing device comprising a ram anda supporting arm extending from the ram to the hood assembly, said rambeing located substantially equidistantly from each tank, said hoodassembly being swingable, in response to actuation of the lift-and-swingdevice, about the ram as a pivot, the outlet of the header and the hoodassembly being so arranged as to make simultaneous connection with thevacuum system inlet and vacuum tank, respectively, when the ram lowersthe hood assembly into place on the vacuum tank, and, means for blankingolf the header outlet not connected to the vacuum system inlet at thesame time as the other outlet is connected to the vacuum system inlet,said means including at least one closure member so disposed as to blankoif the unused header outlet. 2. The vacuum system of claim 1 furthercharacterized in that the means for blanking o the unused header outletincludes a plate carried by a support structure, said plate having asurface complementary to the unused header outlet, said plate, vacuumsystem inlet and open end of each vacuum tank lying in the same plane sothat all meeting surfaces engage simultaneously as the ram lowers thehood assembly into place.

3. A vacuum system for degassing molten metal, said system including atleast a pair of open ended vacuum enclosures, a hood assembly engageablewith the open end of each enclosure alternatively, means for forming avacuum tight seal between the meeting surfaces of the hood assembly andan enclosure when they are in engagement with one another, said hoodassembly having an opening therethrough connected to a header movablewith the hood assembly,

means forming a vacuum tight seal between the hood assembly and theheader,

said header in turn being connectable and disconnectable in vacuum tightengagement to a vacuum system inlet, said foregoing structure therebyforming, when in engagement, a closed vacuum tight system having anopening connectable to a vacuum system inlet,

means for relatively moving the hood assembly, and the header, from oneenclosure to another whereby the hood assembly is aligned with anenclosure and the header with the vacuum system inlet,

said vacuum enclosure, vacuum system inlet, hood assembly, and headerbeing so arranged that sealing engagement between the hood assembly andthe vacuum enclosure, and sealing engagement between the header and thevacuum system inlet, occurs substantially simultaneously,

said vacuum enclosure, vacuum system inlet, hood assembly, and headerbeing so arranged relative to one another that, after making sealingengagement, said sealing engagement is thereafter maintained untilfurther relative movement occurs.

4. The vacuum system of claim 3 further characterized in that the openend of each vacuum enclosure and the vacuum system inlet lie in the sameplane.

5. The vacuum system of claim 3 further characterized in that the meansfor relatively moving the hood assembly, and the header, from oneenclosure to another, is a lift-and-swing device located betweenadjacent vacuum enclosures, said lift-and-swing device having a verticallift device and a hood assembly supporting arm extending outwardly fromthe lift device into operative lifting engagement with the hoodassembly, said hood assembly being pivotable about the left device, anda swing device operatively connected to the hood assembly for pivotingthe hood assembly about the swing device, said lift device being locatedadjacent each vacuum enclosure so that the hood assembly and headeroutlet may be brought into registry with the vacuum enclosure and vacuumsystem inlet, respectively, as the hood assembly swings about the liftdevice.

6. The vacuum system of claim 3 further including dimension stabilizingmeans for insuring vacuum-tight engagement of the sealing surfacesirrespective of temperature variations in the system, said dimensionstabilizing means comprising structural members connecting adjacentsystem components, including the header and the hood assembly, saidstructural members being disposed generally along an extension of adiameter of the components with which they are associated.

7. The vacuum system of claim 3 further characterized in that the headercomprises a vacuum conduit forming a uid iiow path between the hoodassembly and two header outlets, and

further including a pair of closure members so disposed as to makesealing engagement with the unused header outlet when the hood assemblyand header are in sealing engagement with a vacuum enclosure, saidclosure members thereby blanking off the unused header outlet.

8. A system for degassing molten metal, said system including, incombination,

a vacuum enclosure having an opening therein, said enclosure beingconstructed and arranged to contain a quantity of molten metal to bedegassed, a vacuum system, said vacuum system having an inlet, a vacuumconnection, said vacuum connection having an inlet engageabie with theopening in the vacuum enclosure and an outlet engageable with the vacuumsystem inlet,

and movable means for operatively engaging and disengaging the vacuumconnection with the vacuum enclosure and the vacuum system to therebyprovide a gastight fluid iiow path from the vacuum enclosure, throughthe vacuum connection and into the vacuum system,

said ..-'acuum enclosure, vacuum system inlet, and vacuum connectionbeing so arranged that sealing engagement between the vacuum enclosureand the vacuum connection, and sealing engagement between the vacuumsystem inlet and the vacuum connection occurs substantiallysimultaneously.

9. A vacuum system for degassing molten metal in a plant of the typehaving a furnace constructed and arranged to discharge to a molten metaltransfer car, a degassing station for degassing molten metal in atransfer car, a ladle lling station for pouring degassed molten metalfrom the transfer car into a receptacle such as a ladle, and a moltenmetal transfer car and means for moving the transfer car from station tostation, said degassing station including a vacuum system inlet, avacuum conduit for connecting the transfer car to the vacuum systeminlet, and movable means for making alternate engagement anddisengagement between the transfer car and vacuum conduit and betweenthe vacuum conduit and the vacuum system inlet, the engaging surfaces ofthe vacuum conduit, transfer car and vacuum system inlet being soarranged as to make substantially simultaneous sealing engagementwhereby a vacuum may be quickly drawn in the transfer car so that heatloss between the charging station and ladle filling station is kept at aminimum.

10. The vacuum system of claim 9 further characterized in that the meansfor making sealing engagement between the transfer car and vacuumconduit, and between the vacuum conduit and the vacuum system inlet,includes,

a support structure, and

hydraulic cylinder means carried by the support structure andoperatively connected to the vacuum conduit to move said vacuum conduitinto and out of substantially simultaneous sealing engagement with themetal transfer car and the vacuum system inlet, the meeting surfacesbetween the metal transfer car and the vacuum conduit, and between thevacuum 10 system inlet and the vacuum conduit being so posi- 2,290,961Heuer July 28, 1942 tioned as to make substantially simultaneous en-2,852,246 Janco Sept. 16, 1958 gagement When the vacuum conduit is movedinto engagement with the metal transfer car and vacuum FOREIGN PATENTSsystem inlet. 5 1,087,534 France Aug. 25, 1954 References Cited in thele of this patent OTHER REFERENCES UNITED STATES PATENTS Making, Shapingand Treating of Steel, charts between 2,177,716 Heuer Oct. 31, 1939pages 282-283 and 398, 399, 6th edition, 1951.

1. A VACUUM SYSTEM FOR VACUUM DEGASSING MOLTEN METALS, SAID SYSTEMCOMPRISING A PAIR OF VACUUM TANKS, SAID TANKS BEING OPEN AT THEIR UPPERENDS, A HOOD ASSEMBLY, SAID HOOD ASSEMBLY INCLUDING A HOOD ENGAGEABLEWITH THE UPPER OPEN END OF EACH TANK AND ADAPTED, WHEN IN ENGAGEMENTWITH A TANK, TO FORM AN AIR-TIGHT SEAL THEREWITH, A HEADER, SAID HEADERHAVING AN INLET OPENING INTO THE HOOD AND A PAIR OF OUTLETS, EACH OUTLETBEING CONNECTABLE, IN TURN AND DEPENDING UPON THE POSITION OF THE HOODASSEMBLY, TO A VACUUM SYSTEM INLET, A LIFT-AND-SWING DEVICE, SAIDLIFT-AND -SWING DEVICE COMPRISING A RAM AND A SUPPORTING ARM EXTENDINGFROM THE RAM TO THE HOOD ASSEMBLY, SAID RAM BEING LOCATED SUBSTANTIALLYEQUIDISTANTLY FROM EACH TANK, SAID HOOD ASSEMBLY BEING SWINGABLE, INRESPONSE TO ACTUATION OF THE LIFT-AND-SWING DEVICE, ABOUT THE RAM AS APIVOT,